The present invention relates to novel bituminous-based roofing compositions comprising a bituminous material suitable for roofing, crumb rubber, and a polysulfide, to the method of forming such roofing, and to improved polysulfide roofing.
The parent application, whose entire specification, drawings, and claims are specifically incorporated herein by reference, discloses novel roofing, including roofing shingles utilizing elastomeric polysulfides. Such roofing is resistant to cracking and hail damage. Due to the cost of polysulfides, such roofing is costlier than existing roofing compositions and shingles and can mitigate against its usage.
Presently, low cost materials for roofing are bituminous materials, such as asphalt. Roofing asphalts, typically Types I through IV, are commonly used to form roofing. For use on flat roofs, they are delivered, usually in block form, to an asphalt kettle where the asphalt is heated to a molten or liquid state and the molten asphalt then applied to a surface to form the roofing. After application, the asphalt solidifies back to its rigid state. Asphalt shingles have also been used.
Among the many problems with roofing asphalts is the fact that they are brittle, particularly at low temperatures, have poor structural strength, and upon exposure to the elements they tend to crack and suffer degradation from ultraviolet radiation. As a consequence, they do not have suitable service life and are susceptible to severe damage by hail. Efforts to overcome some of the defects of such type of roofing is to include certain types of polymers with the asphalt, such as is shown, for example, in U.S. Pat. Nos. 4,032,491 and 4,196,115. These are done in an effort to make the asphalt roofing less brittle and to have suitable properties at low temperature. Other efforts to improve the undesirable properties of the asphalt include the addition thereof of rubber crumb layers, as is shown in U.S. Pat. No. 3,547,674.
However, none of these compositions discussed above in the prior art has sufficient strength and resistance to damage from hail. The brittle nature of the asphalt is such that none of the prior art compositions discussed above has suitable low temperature properties, resistance to UV degradation, as well as impact-resistance so as to resist hail damage.